As demand for processing power across different environments continues to increase, the need for multiple processors executing in a multi-processing environment has grown. Additionally, in different environments, the amount of memory could be limited due to cost and/or space restraints. Therefore, in certain multi-processor environments, such as a symmetric multi-processing environment, memory is shared among the different processors and thereby segregated to allow use of different portions of the memory by each of the different processors. However, for symmetric multi-processing, the same operating system is employed for running on both processors.
However, for certain applications, the different processors in a multi-processing environment are running different operating systems. For example, in a communications networking environment, given control cards within network elements may require a number of processors such that each processor is running a different operating system in order to accommodate the various functionality required for these control cards. To help illustrate, one processor could include a real time operating system in order to handle routing of data received within the network element, while a second processor could include a non-real time operating system in order to handle provisioning and configuration of the network element.
Disadvantageously, problems arise in a multi-processing environment wherein multiple processors are designed to share a same memory while executing different operating systems. Examples of such problems are encountered in the handling of exceptions, such as interrupts, by the different operating systems. In particular, the architecture of processors is typically such that they reserve an address space within memory to act as the exception handling vector addresses for handling, at least initially, the exceptions received by the processor. However, different operating systems generally handle their exceptions differently. Therefore, when two processors of a same type are executing different operating systems, there is a conflict in the handling of exceptions as both processors are designed to use the same address space in memory for initial exception handling.
Therefore, in typical multi-processing systems wherein this conflict of exception handling address space arises, a processor queries the memory controller to determine which processor it is (and therefore which operating system it is running) and processes the exception based on this knowledge. Disadvantageously, each time an exception is received, the processor must perform this query of the memory controller, which slows down the processing of these exceptions as this is a query that is external to the processor that can require multiple clock cycles to process.